Cost and durability issues have made it difficult to commercialize fuel cells. Fuel cells utilize a catalyst that creates a chemical reaction between a fuel, such as hydrogen, and an oxidant, such as oxygen, typically from air. The catalyst is typically platinum loaded onto a support, which is usually a high surface area carbon.
Some durability issues are attributable to the degradation of the support caused by corrosion. Electrochemical studies have indicated that the corrosion depends strongly on surface area and morphology structure of carbon. For example, it has been reported that carbon with high surface area, such as ketjen black, can corrode severely at potentials experienced during start and stop cycling of the fuel cell causing a dramatic loss in fuel cell performance. Accordingly, to overcome this particular durability issue, it may be desirable to use a support other than carbon that is more chemically and electrochemically stable.
One possible alternative support for a catalyst is a metal oxide or metal phosphate. Metal oxides/phosphates can typically have a high surface area and good corrosion resistance in low temperature fuel cell applications. However, most of those high surface area metal oxides/phosphates are not conductive, and are extremely hydrophilic. Hydrophilic supports can cause sever problems, such as flooding, which leads to significant drop in cell performance, especially at high current densities. As a result, metal oxide/phosphate based supported catalysts have not been applied to low temperature fuel cells.
What is therefore needed is a modified metal oxide/phosphate based supported catalyst that is suitable for use in a fuel cell environment.